Traditionally pulp derived from fast growing trees, such as pine, has been used as the raw material for containerboard packaging. The containerboard is comprised of linerboard and medium. The linerboard is usually made from softwoods, which have the longest fibers and produce the strongest containerboard. On the other hand, the medium is made from hardwood fibers, which tend to be shorter and stiffer than softwood fibers. In recent years, the use of recycled, old corrugated container (OCC) material has grown in popularity as a linerboard or corrugated medium because of concerns about environmental sustainability. However, the OCC frequently requires repulping and de-inking processes. As such, the recycled fibers get shortened, weakened and contaminated as the number of recycles increase. Coupled with an increased demand and utilization of recycled fiber by many corrugated cardboard producers, the cost of recycled fiber has also increased. The move toward single stream recycling is causing an increase in contamination (staples, plastic tapes and hot melt adhesives) of the existing recovered fiber streams. Critical performance requirements such as strength (compression, edge crush, burst, and tensile strength), stiffness, or rigidity, moisture resistance, grease resistance and freeze/thaw tolerance can be more difficult to achieve with recycled paper or paperboard.
Hybrid fiber compositions comprising non-wood alternative natural fibers such as those derived from algae, corn stover, wheat straw, rice straw and the like would be an option to resolve such aforementioned issues. Fiber substitution in corrugated medium using land-based non-wood alternative fibers such as wheat straw alone may be challenged at a high level of inclusion. One of the factors is related to the fines associated with pulp fibers. Wheat straw fiber contains more fines (about 38-about 50%) than hardwood (about 20 to about 40%) or OCC (about 20-about 25%) fibers. This being the case, wheat straw fiber dimensions (fiber length and diameter) are comparable to hardwood fibers, such as those pulped from maple and oak, but shorter than OCC fibers due to the presence of softwood fibers in recycled containerboard materials. The fines could be viewed as a filler; however, having more fines from wheat straw pulp compared to others doesn't contribute to strength.
Red algae are one of the seaweeds, which belong to the division Rhodophyta, a part of Gelidiaceae family. Its fiber obtained after agar or bioethanol extraction has a high aspect ratio and surprisingly enhances corrugating medium mechanical properties such as tensile index, ring crush, burst index and tear index, etc. in hybrid fiber compositions. The presence of red algae fiber enables corrugated medium to meet or exceed the primary mechanical property requirements which, allows a high proportion of non-wood fibers, such as wheat straw, to be effectively utilized yet still fully meet product performance demands. Thus, the use of non-wood alternative fibers would be more eco-friendly, represent a significant shift from the use of conventional raw materials (hardwood pulp or OCC) and result in potential cost savings to various manufacturers.
Therefore, there exists a need for providing wood-alternative pulp materials to replace a portion of conventional fiber materials used in containerboard packaging. Additionally, there is a growing need for stronger, light weight corrugated materials that allow for packaging weight reduction. Although previous attempts to using alternative fibers to produce construction and furniture applied composite boards, there is a lack of sustainable attempts to produce non-wood natural fiber-based corrugated medium to be used in containerboard packaging applications. As a result, the present invention fills such gaps by providing wood-alternative materials that can be used for environmentally sustainable containerboard packaging.